Electronically controlled needle selection system for knitting machines

ABSTRACT

A knitting machine having individually operable needles, pattern information carrier means movable in sympathy with the machine and an electronically controlled needle selection system which, at the dictates of the pattern information and via butts associated with the needles, selectively controls the latter. Each needle has its own magnetic actuator unit. Each such unit includes a light responsive detector responsive to light signals transmitted to it by the pattern information carrier means. A light level detector circuit provides a step voltage output when the level of signal received by the detector exceeds a threshold value. When triggered by this output a monostable circuit produces an output pulse. This pulse energizes an opposing winding associated with a permanent magnet included in the unit to re-direct the attractive force of the magnet. Associated with each unit is an armature normally retained by the magnet but releasable therefrom, to change the path of flux, to exercise selective control over corresponding needle.

United States Patent 11 1 Bliss-Hill et a1. May 22, 1973 54] ELECTRONICALLY CONTROLLED 479,738 11/1969 Switzerland ..66/75 NEEDLE SELECTION SYSTEM FOR 488,837 /1970 Switzerland ..66/75 KNITTING MACHINES P E W C R 1d rimary xaminer m. arter eyno s [75] Inventors: Herbert Brian Bliss-Hill, Evlngton; A T l d Eric William y, Kirby ttorney arson, ay or an Hlnds Muxloe, both of England [57] ABSTRACT [73] Asslgnee: f g Lmmed Le- A knitting machine having individually operable nee- Ices ng an dles, pattern information carrier means movable in [22] Filed: Dec. 2, 1970 sympathy with the machine and an electronically controlled needle selection system which, at the dictates [21] Appl' 94427 of the pattern information and via butts associated with the needles, selectively controls the latter. Each [52] U.S. Cl. ..66/50 R needle has its own magnetic actuator unit. Each such [51] Int. Cl. ..D04b /78 nit includes a light responsive detector responsive to Field 0f Search 50 light signals transmitted to it by the pattern informa- 154 A tion carrier means. A light level detector circuit provides a step voltage output when the level of signal References Cited received by the detector exceeds a threshold value. UNITED STATES PATENTS When triggered by this output a monostable circuit produces an output pulse. This pulse energizes an op- 3,141,3l6 7/1964 McCarthy et a] ..66/154A posing winding associated with a permanent magnet 3,317,735 5/1967 l 66/50 R X included in the unit to re-direct the attractive force of 3,365,916 1/1968 Ribler et al. 1 ..66/ R the magnet. Associated with each unit is an armature 3,449,928 Schmidt CI 3.1 R normally retained the magnet but releasable FOREIGN PATENTS OR APPLICATIONS therefrom, to change the path of flux, to exercise selectlve control over corresponding needle. 287,187 3/1928 Great Britain ...66/50 R 1,163,052 9/1969 Great Britain ..66/ 9 Claims, 9 Drawing Figures Patented May 22, 1973 3,733,855

8 Sheets-Sheet 1 lll I05 Pmmd May 22, 1973 3,733,855

8 Sheets-Sheet I 8 Sheets-Sheet 3 Patented May 22, 1973 8 Sheets-Sheet 5 Patented May 22, 1973 8 Sheets-Sheet 6 NE 1 7 r UVQ Vi Patented May 22, 1973 8 Sheets-Sheet 8 mQQQmQ ELECTRONICALLY CONTROLLED NEEDLE SELECTION SYSTEM FOR KNITTING MACHINES This invention relates to knitting machines of the general class equipped with individually operable knitting needles, and means, including one or more pattern information carriers movable in sympathy with the machine, for exercising selective and individual control over these needles, through the medium of associated butts which, according to predetermined patterning requirements, are either left undisturbed or are acted upon in any desired manner to influence the corresponding needles in different ways according to the nature of the patterned knitted fabric to be produced.

The term associated butts, is used herein in a generic sense and is intended to be sufficiently broad to cover not only the more usual case in which the butts are provided on jacks, sliders or like instruments separate from the needles, but also a case in which the butts are on the needles themselves.

Although principally intended for application to multi-feed circular jacquard knitting machines of the rotary needle cylinder type, there is no limitation in this respect since the invention may be applied to any other appropriate types of circular knitting machines, as well as to flat knitting machines having either a single needle bed or two opposed needle beds.

For convenience and simplicity in the following further description, it will be assumed, without any limitation of the broad scope of the invention, that the butts associated with the needles are selectively acted upon suchwise as to cause some needles to knit and others to non-knit.

In particular, the invention has reference to an electronically controlled needle selection system for a knitting machine of the general class referred to.

It has previously been proposed to apply such a needle selection system to a knitting machine wherein the aforementioned associated butts are all disposed at the same level by employing magnetic means for effecting the single level selections. It is also known, on such a machine, to adopt electro-mechanical transducers which are arranged for action upon needle-actuating jacks, either directly or through the medium of individual spring selector wires, for effecting the single level selections.

It has also been proposed to apply an electronically controlled needle selection system to a multi-feed circular jacquard knitting machine in which the associated butts are so disposed in a multiplicity of planes as to enable the butts in any one plane to be well spaced apart with time intervals between them. In such a case, both magnetic means and also electro-mechanical transducers have been used to effect the necessary multi-level selections. For example, according to one particular prior proposal, selectively operable transduceractuated butt displacing devices are arranged inthe several butt planes, the system including pattern control means bearing information adapted to influence actuation of the said butt displacing devices, an electronic pattern scanning means for systematically scanning the information borne by the pattern control means and for converting it into electrical signals, and means for thereupon routing such signals to desired ones of the transducer-actuated butt displacing devices.

The various previously proposed electronically controlled needle selection systems mentioned above are subject to disadvantages. Thus, for instance, in a singlelevel selection system there is an extremely short time available (approximately 1 ms) between any two butts in which to effect an electronic selection. As regards a multi-level selection system, the electronics required to provide the many levels or information are prohibitively expensive.

Moreover, when using electro-mechanical transducers in either system the pivot bearings, end stops etc. have a very limited life, necessitating frequent renewals of components.

The object of the present invention is to provide, in a knitting machine of the class concerned, a generally improved electronically controlled needle selection system which combines the advantage and has none of the disadvantages of both of the previously proposed systems. That is to say, the aim is to provide a system which will make possible single level magnetic selections and yet at the same time provide a sufficiently long period of time in which to satisfactorily effect each selection.

According to this invention, each individually operable knitting needle in the machine has its own magnetic actuator unit comprising, in combination, a detector responsive to signals transmitted thereto at the dictates of movable pattern information carrier means; a level detector circuit adapted to provide a step voltage output when the level of signal received by the detector exceeds a predetermined threshold value; a monostable circuit capable of producing an output pulse when triggered by the output from the said level detector circuit; and a permanent magnet having in association with it an opposing winding for flux re-direction, the said winding being energizable in response to an output pulse produced by the monostable circuit suchwise as to re-direct the attractive force of the magnet.

Each magnetic actuator unit has in association therewith an armature which is arranged to be normally attracted to and retained by the permanent magnet but releasible therefrom upon re-direction of flux to initiate selective actuation of the knitting needle, e.g. to knit or miss-knit, as the case may be.

Preferably, the armature associated with each permanent magnet consists of a relatively thin spring wire which, whenever released for movement away from the said magnet, is either acted upon mechanically or functions mechanically to influence the relevant needle either directly or, more usually, through the medium of a jack housed in the same groove or trick in the needle bed, or the relevant needle bed, as that accommodating the said needle. An advantage of employing spring wires as armatures is that their inherent springiness can be relied on to assist in moving them away from the permanent magnets at such times as the magnetic retaining forces of the latter are re-directed. Conversely, a spring wire can be readily cammed against the spring action from a normal position in which the wire is in a relaxed condition into a position in which the said wire is in contact with the corresponding permanent magnet and is retained thereby against the reaction of the spring bias.

The knitting machine essentially includes a cam, in advance of the or each needle selecting station, for forcibly moving all of the armatures seriatim into contact with their respective permanent magnets preparatory to seiected ones of these magnets having their flux re-directed to release the corresponding armatures, whereas the remaining magnets are unaffected and retain their associated armatures, all at the dictates of the moving pattern information carrier means.

In accordance with an essential feature of the present invention, the said cam or cams is or are so arranged that there is a maximum possible distance between the point at which a signal is transmitted to the level detector of each magnetic actuator unit and the point at which the corresponding armature, if selected, is released to initiate mechanical selection of the relevant knitting needle. This time-extending distance may be of the order of from, say, ten to twelve needle pitches in the case of a circular 48-feed knitting machine. Thus, this substantial extension of the time available in which an electronic selection can be effected represents one of the main advantages of the improved system. The potential frequency of the signals determined by the moving pattern information carrier or carriers, must, of course, be the same as the frequency of the relative movement of needle tricks or grooves past the means employed to transmit such signals to the level detectors: but since each trick or groove has its own magnetic actuator unit, the latter has, in fact, a time equivalent to a plurality (e.g. ten to twelve) needle pitches in which to operate.

In the principal application of the invention to a multi-feed circular knitting machine of the rotary needle cylinder type there is at each feed a control station at which is provided means for transmitting signals to predetermined ones of the level detectors passing by the same as the needle cylinder rotates.

But in a flat knitting machine in which the or each needle bed is stationary, the means for transmitting signals to selected level detectors would be mounted on the traversible cam carriage so that in this case the said means pass by the stationary detectors at each traverse of the carriage in either direction. A flat knitting machine may be provided with only one feed.

Preferably, the level detectors are in the form of light-responsive devices so that each detector provides a step voltage output when the level of light received by it exceeds a predetermined threshold value.

Advantageously, the means at the or each feed for transmitting light signals to the light-responsive detectors may consist of a fiber-optic light guide. Such a light guide consists of a flexible tube containing a bundle of light-transmitting fibers and is now well known and commercially available.

The or each pattern information carrier may conveniently be in the form of a programmed control tape adapted to be driven synchronously with the knitting machine. Such a tape would have one row of information per feed, one end of a corresponding tubular fiberoptic light guide terminating adjacent to the row whilst the other end of the said guide is so arranged at the feed as to be passed by, or to pass, the light-responsive detectors.

In order that the invention may be more clearly understood and readily carried into practical effect, a specific form of the improved electronically controlled needle selection system as applied to a multi-feed double jersey jacquard machine of the rotary needle cylinder and dial type will now be described with reference to the accompanying drawings, wherein,

FIG. 1 is a general perspective view of the said machine,

FIG. 2 is a detail sectional view taken through the knitting head of the machine showing the needle cylinder, the associated cam box, one of the magnetic actuator units and the corresponding spring wire armature which is releasable from the permanent magnet to initiate selective actuation of the relevant needle,

FIG. 3 is a diagrammatic underside plan view of cams employed at selecting stations for controlling and moving spring wire armatures seriatim into contact with their respective permanent magnets and also cams for rocking selector members engaged with patterning jacks in the manner and for the purpose hereinafter to be described,

FIG. 4 is a detail vertical sectional view through the cylinder carriage and associated parts beneath those shown in FIG. 2,

FIG. 5 illustrates the general electricai circuit layout used for needle selection purposes,

FIG. 6 is a detail vertical sectional view taken through the base of the knitting machine and shows a rotary transformer through which electrical power is fed to the needle actuator units,

FIG. 7 is a diagrammatic representation of the electrical circuitry, including the monostable circuit associated with each of a multiplicity of circuit boards such as that shown in and hereinafter to be described with reference to FIG. 4,

FIG. 8 is an artists impression diagrammatically illustrating a particular arrangement of control tapes, light sources, illuminating heads, reading heads and fiber optic light guides for carrying the invention into effect, and

FIG. 9 is a side view of the permanent magnet and the associated opposing winding for flux re-direction included in one of the needle actuator units.

Referring to FIG. 1 of the drawings, the machine to which the illustrated example of the invention is applied is generally designated by the reference numeral 100. This machine is a double jersey jacquard machine of the rotary needle cylinder and dial type. The hollow base 101 supports the rotary knitting head 102 of the machine, and a conventionally mounted superstructure 103 carries the yarn packages in the form of cones 104 of variously colored yarns. At 105 are indicated main switches for starting, stopping and inching the machine, whereas at 106 are shown ventilating fans.

The rotary needle cylinder of the machine shown very generally in FIG. 1 and in more detail in FIG. 2 is designated by the numeral 107. This cylinder is cut with tricks 107a to accommodate independent latch needles such as 108 (FIG. 2) each having thereon an operating butt 108a arranged to be acted upon by cams, such as 109, 110, housed in a stationary annular cam box or shell 11]. This cylinder cam box is mounted upon a fixed bed ring 112 shown both in FIGS. 1 and 2.

In FIG. 1, moreover, the patterned fabric produced on the machine is shown being drawn down by a rotary draw-down mechanism and finally rolled up upon a driven reel 121 housed within the hollow base 101.

At 122 in FIG. 1 is depicted a punched tape control unit which is mechanically connected at 123 to, and driven from, the knitting machine. The tape T is shown passing over a sprocket-like pulley 156.

Referring again to FIG. 2, it will be seen that there is provided beneath each cylinder needle 108, in the same trick 107a, a patterning jack 127. Each jack is pivotally located at its lower end 127a in the bottom of the cylinder trick 107a and held there between the back of the cylinder trick and a fixed projection 128a on the cylinder carriage 128. The vertical movement of the patterning jack 127 is governed by cams 119 and 110 acting on a butt 1271; at the top of the said jack. The jack is capable of being swung inwardly more deeply into its cylinder trick in order to disengage its top butt 127b from its controlling cams. To permit of such an inward swinging movement of the jack 127, the cylinder trick 107a is made deeper at the location 107b. In this example, the butt 127b is one of the associated butts previously referred to herein.

At a point disposed approximately midway between its ends, each patterning jack 127 is furnished with a hook 1270 and recess 127d arranged to co-operate with a hook 130a on the inner end of a horizontal selector member 130. The arrangement is such that normally each patterning jack 127 is held in its forwardly tilted position by virtue of the hook 130a pulling on hook 127c to maintain the butt 127b engaged with its controlling cams so that the corresponding needle 108 will knit. By pushing a selector member 130 inwardly the hook 130a thereon will contact and push against the back of the recess 127d in the corresponding patterning jack 127 with the result that this jack will be tilted inwardly to withdraw its butt 127b from the track T between the cams 110 and 119 so that the corresponding needle will not knit.

In an annular part of the machine rotating together with but in the outside of the needle cylinder 107 are mounted n needle actuator units 132 where n equals the number of needles 108 in the needle cylinder. These actuator units 132, hereinafter to be more fully described, are mounted on a ring 131 which is in turn supported on an outwardly directed flange 1281) of the cylinder carriage 128. Each actuator unit includes a spring wire armature 133 held at its outer end substantially horizontally in blocks such as 134, supported on the ring 131. An inner portion of each spring wire armature is freely supported in comb type portions 131a of a ring 131. A cover ring 135 is fitted onto the blocks 134 to cover and thereby protect the wires 133 from outside influence. The inner extremity of each spring wire armature 133 co-operates with the upper end of a further spring member 136 mounted substantially vertically and held at its lower end in blocks, such as 137, supported on the cylinder carriage 128. The upper end of each spring member 136 is of stepped configuration having two working edges 136a and 136b.

The selector members 130 are mounted freely in comb members 138. By freely mounted it is to be understood that the selector members 130 are not fixed but held by friction to the extent that they are able to pivot and slide as dictated by operating cams. At its outer end each of these selector members is provided with a butt 13011 for co-operation with edge 13Gb of the corresponding spring member 136. A further butt 130a disposed mid-way along the top edge of the selector member 130 is operated on by cams 139, 141.

There is a selector member 130, a spring wire armature 133 and a spring member 136 all as just described to each needle 108 and associated patterning jack 127 in the needle cylinder, and these parts co-operate in the following manner to cause the needles to knit or nonknit.

Reference will now be made to FIG. 3 in which the rotational direction of movement of the needles and associated elements is shown by the arrow designated A. At the commencement of selection at the first selecting station shown in FIG. 3, the cam face 140a of cam 140 pushes on operating edges 136a of spring members 136 which are not already held in the radial inward position by armatures 133 as a result of selection at the previous station to push the latter clear of the ends of spring wire armatures 133. Immediately prior to action on edges 1360 by face 140a a cam 141a lowers butts 13% of selectors 130. Thus, the jacks are selectively rocked. Immediately this is accomplished the spring wire armatures 133 are cammed down by cam 143 onto their respective actuator units 132 where they are held by magnetic attraction after having passed holding-down land 143a on cam 143. The actuator units 132 are then influenced to release selected spring wire armatures 133 as will be hereinafter described.

At the same time as selection takes place, a cam face 139a of a cam 139 rocks all the selector members so that the butt 130b of each such member is clear of the upper end of the corresponding spring member 136, immediately following which a cam face 13% on said cam 139 acts on butts 1300 to push radially outwards those selector members 130 which were not already radially outward as a result of non-selection at the last station, whereby all the butts 127b of the patterning jack 127 are in the lifting jack track T. Selected spring members 136 are then allowed to move outwards under their own inherent spring tension to follow a cam face 14% at the selecting station. It is only selected ones of these members 136 which will operate in this way, as the non-selected ones will be held inwards due to their operating edges 136a being engaged with the inner extremities of those spring wire armatures 133 which were previously released from their actuator units 132.

This selective operation accordingly now leaves some of the spring members 136 in front of and others behind the positions of butts 13% of those selector members 130 which are tilted upwardly to position the said butts clear of the upper ends of the spring members 136. A cam face 141a of a cam 141 at the selecting station is now engaged by the outer end portions 130d of relevant selector members 130 which as a consequence are tilted downwardly in order that corresponding butts 13% shall now be lowered to a position where some spring members 136 are in front of, and some behind, the butts 130b.

A cam 142, identical to cam 140, is provided at the second selecting station shown in FIG. 3 but its leading cam face 142a in fact performs the relevant selecting operation of the first selecting station. This particular operation is performed by virtue of the cam face 142a pushing on the front operating edges 136a of selected spring members 136 whose rear operating edges 136k push on butts l30b of corresponding selector members 130. As previously described herein this action results in the hooks 130a of the rearwardly pushed selector members 130 pushing on the corresponding patterning jacks 127 to disengage their butts 12717 from the jack lifting track T causing the relevant needles not to knit.

This entire operation as just described for the first selecting station is then repeated for each subsequent selecting station around the machine.

To enable such a needle selection system to operate it is necessary that electrical power is fed to the needle actuator units 132 and, since the latter rotate together with the needle cylinder 107 it is necessary to provide either slip rings or, as in the specific illustrated example, a rotating transformer.

Such a rotating transformer, generally designated 150, is illustrated in FIG. 6. The transformer is located in a suitable housing within the base of the knitting machine below the conventional fabric take-down rollers. In this specific example the rotary transformer is mounted in a main housing 151 supported just clear of the floor by the legs 152. Mounted on a bearing 153 within the housing 151 is a driving bracket 154 for the rotating part, i.e. rotor, 155 carrying the secondary windings of the rotary transformer. This driving bracket 154 is in turn driven in unison with the needle cylinder 107 through the medium of gear teeth 154a. The rotor 155 is also supported by bearings 156 and 157.

The stator 158 carrying the stationary or primary windings of the rotary transformer 150 is housed within a subsidiary casing 151 which also houses the rotor bearings 156 and 157 and is supported by the main housing 151. Three phase AC power is supplied to the stator 158 within conduits 159 by stator leads 160. This electrical power is induced into the rotor 155 and passed on to power supply packs 161 to 167 spaced circumferentially around the base of the machine as shown in FIGS. 1 and 6. The power supply packs are used for converting the AC supply into DC for operating the opposing windings 199 associated with the permanent magnets PM of the needle cylinder units 132. In particular the packs 161 to 166 are used to supply the 12 volts power for the windings 199 of the actuator units and supply pack 167 to supply i 12 volts stabilized power for operating the selection of that power as will be described later.

The DC power is now passed from the supply packs 161 to 167 to a number of bus-bars 168a to 168p which are in turn connected to a number of electronic circuit boards such as 169 (see FIGS. 4 and Each circuit board in this specific example carries the electronic circuitry for twelve actuator units 132 one of which circuits is shown in FIG. 7. The power supply to each board 169 is taken from several bus bars 168 in order to ensure an even distribution of the power load. Thus, in FIG. 4 the two bus bars 168a and 16812, supplied from the power pack 161, are connected to a series of the circuit boards. The poser supply from pack. 167 is connected to a voltage stabilizer 178 and then to three bus bars 168g, 1681:, 168f which are in turn connected to all the circuit boards around the machine.

Further connections to each circuit board 169 are shown in FIGS. 4 and 5 these including one connection 170 for each individual one of a set of twelve PE. (i.e. photoelectric) cells 171, and one common connection 172 for each such set. As stated before, each circuit board 169 is a common carrier for twelve circuits connected to their respective P.E. cells and needle actuator units 132. The connections to the needle actuator units are designated by the numeral 173.

Each circuit board 169 is mounted radially below the needle cam box as shown in FIG. 4. The said boards are slotted in between pin heads 174, 175, 176 and 177 and are therefore easily removable by first removing brack ets 182 and 184 which are distributed around the machine in a complete circle.

The photo-electric cells 171 are mounted in the required sets on boards 179 and 180 which are fixed by screws, such as 181, to the brackets 182. The latter are secured upon a main rotating member of the frame of the machine.

Fiber optic light guides 183 are fitted into the brackets 184 which are mounted on a main stationary member 186 of the machine frame, these light guides being in close proximity to, and in heightwise alignment with, the RB. cells 171. Cover plates 187 are attached to the tops of the brackets 184 in order to keep the spaces occupied by the RB. cells free from dust and outside interference. An additional seal 188 is also placed at the back of the RB. cells 171 allowing only the respective connectors 170 and 172 through to the circuit boards 169.

In FIG. 4, the PE. cells 171 and the fiber optic light guides 183 are shown at two heights; thus, in the illustrated example, there are two fiber optic light guides at each feed station arranged one above the other. There is one P.E. cell 171 to each needle 108 in the machine, these cells being arranged in two horizontal rows around the machine in a staggered relation such that alternate RB. cells are actuated by light guides at the higher level whilst intermediate RB. cells are actuated by light guides at the lower level. In this particular arrangement, quoted merely by way of example, the higher level light guides and the lower level light guides are respectively connected to reading heads arranged to scan respective punched control tapes running in synchronism with the machine.

Other appropriate arrangements of PE. cells 171 and fiber optic light guides 183 may, however, be applied to the herein described needle selection system. For instance, in one such alternative arrangement there may be one row of RB. cells and light guides connected to one reading head arranged to scan a single punched tape. Or two rows of RB. cells and light guides as described above may be connected to one reading head scanning one punched tape. Yet again, a multiplicity of heightwise spaced rows of RB. cells and light guides may be controlled from one or a multiplicity of reading heads scanning one or a multiplicity of punched tapes.

One specific arrangement of control tapes and reading heads will now be described with reference to FIG. 8. In this arrangement, two punched control tapes 189 and 190 are set out with the necessary information for controlling respectively alternate and intervening needle actuator units 132 at each feed.

A multiplicity of fiber optic light guides 192 (48 to each control tape in this example) are used to transmit light from either a common light source 191 or a plurality of such light sources to an illuminating head 193. Each illuminating head is arranged at one side of the relevant tape in such a way that each light guide 192 is directed onto one longitudinal row of information on the said tape. A reading head 194 is so located at the opposite side of each control tape that one fiber optic light guide 183 is directly over a corresponding longitudinal row of information and in line with one of the light guides 192, there being, of course, forty eight light guides 183 to each reading head, that is to say one for each feed of the knitting machine. With such an ar-- rangement there is a minimum amount of light dissipation outside of its intended paths through the control tapes.

In FIG. 7 is represented one of a number of identical circuits, including the monostable circuitry on each circuit board 169, the chain dotted line in this figure defining the area of that board. Each such circuit includes a level detector in the form of a photo-voltaic cell 171 the volt output from which is fed into a differential amplifier 195 with a feed back circuit 196. This cell 171 is, of course, one of the PE. cells shown in FIG. 5. When, as light starts to pass through a hole in a control tape and along a relevant light guide 183 to the photovoltaic cell 171, the illumination intensity reaches a pre-determined level the Schmitt trigger action of the circuit causes a fast transition in output voltage from a positive to a negative value at point X. The light intensity continues to rise to a maximum as the hole in the tape passes between the relevant aligned light guides 192 and 183 and as the photo-voltaic cell 171 passes the end of the light guide 183, after which the intensity will start to fall-off until a next predetermined level of intensity is reached which is higher than the first illumination intensity. At this point a fast voltage transition in the opposite direction takes place at point X. The difference between the two levels of illumination intensity determines the hysteresis of the circuit so that unrequired voltage oscillations do not occur in the amplifier 195. The hysteresis action normally associated with a Schmidt trigger is contained up to the point X in FIG. 7. Such oscillations might otherwise occur due to vibration effects on a knitting machine which has been stopped causing slight backward, i.e. reverse, movement of the needle cylinder 107. The switching levels of the Schmitt trigger circuit are set to values of maximum sensitivity compatible with cross talk of light at the reading head 194 and between the photo-cells 171 and light guides.

Although the above description refers specifically to a photo-voltaic cell it could equally well apply to any other appropriate type of RE. cell such as a photoresistive cell or a photo-transistor, which in turn feeds a Schmitt trigger circuit with input hysteresis.

The output from X further consists of a network of two transistor stages 205 and 206, a resistor 197 and a capacitor 198 in series on the input side. This network receives a step voltage transition in the negative direction from the Schmitt trigger circuit as just described when the illumination intensity reaches the lower predetermined level. This causes a capacitor 198 to charge through the transistor 205 so that current is passed through a selector via transistor 206 for a period of time determined by the time constant of the input network capacitor-resistor 197, 198. The amplifier may, however, be switched-off earlier than this by the positive voltage transition, that is transition in the opposite direction as previously described; such a condition may occur at speeds higher than that at which a knitting machine is at present expected to run.

Current from one of the power supply packs 161 to 166 is supplied through respective bus bars 168 to current input line 200, and current from the power supply pack 167 is supplied through the voltage stabilizer 178 to a current input line 201. The current to the last mentioned line is normally routed through resistors 202 and 203 to earth at 204, but upon the operation of the Schmitt trigger circuit it is routed through the resistor 197 and capacitor 198 to switch on transistor 205. When transistor 205 is switched on, a current from input line 200 is routed through it to switch on transistor 206. Upon switching on of the latter, current is caused to pass along the input line 200 to earth at 207 and in so doing energizes the coil 199 of the permanent magnet PM of the needle actuator unit 132.

In order that the current passing to the coil 199 shall be strictly regulated it is first passed both through resistance 208 and current limiter 209 which ensure that the coil 199 does not overheat and damage in the event of the circuit to earth 207 remaining closed.

The actual needle actuator included in each needle actuator unit 132 accordingly comprises a permanent magnet PM and an opposing winding, (viz. the coil 199) for flux re-direction. Such a needle actuator is shown in detail in FIG. 9: as will be seen it consists of a center pole piece 210 made of a soft magnetic material around an upper part of which is wound the coil 199. At opposite sides of the root of the center pole piece 210 are magnets 211 and 212, and surrounding the whole are outer limbs 213 made of a ferrous material. Due to the accuracy requirement with this type of needle selection on a knitting machine it is advantageous that a pair of magnets 211 and 212, common to several of the magnetic actuator units, shall be arranged to span all of the latter. In this case, spacer pieces 214 made of non-ferrous material are placed between adjacent center pole pieces 210.

Normally, the magnetic flux flows in the path and direction shown by dotted lines 215, thereby attracting the relevant spring wire armature 133 towards the free end of the center pole piece 210, but upon energization of the coil 199, as previously described, the magnetic flux is re-directed to flow in the path and direction shown by dotted lines 216 thereby releasing the spring wire armature 133.

As will be appreciated from the foregoing description, depending on the type of machine to which the invention is applied, the light-responsive detector of each magnetic actuator unit passes across, or is passed transversely by, the relevant fiber-optic light guide provided at the or each feed control station thereby receiving or not receiving a light signal or pulse as determined by the programmed tape of the appropriate tape, as the case may be. Each light signal or pulse received from a fiber-optic light guide by a light-responsive detector will, as previously mentioned, vary in intensity, rising from a low level to a peak and subsiding again to the low level, as a consequence of which the voltage output from the said detector will vary commensurately: this is why it is necessary to combine with each lightresponsive detector a level detector circuit designed to provide a step voltage output only when the level of light received by the light-responsive detector rises above a predetermined threshold value.

We claim:

1. A circular knitting machine which includes a rotating tricked needle cylinder bed; individually operable knitting needles in said needle cylinder; pattern information carrier means movable synchronously with the machine but not rotatable with the needle cylinder; and an electronically controlled needle selection system which, at the dictates of the said pattern information carrier means, and through the butts associated with the needles, exercises selective and individual control over the latter so that some are influenced in one way and others in another way according to the nature of the patterned knitted fabric to be produced; said machine being characterized in that each individually operable knitting needle therein has its own magnetic actuator unit, all said magnetic actuator units being movable in rotation with the needle cylinder, each magnetic actuator unit comprising, in combination, a detector responsive to signals transmitted thereto at the dictates of the movable pattern information carrier means; a level detector circuit for each needle, each circuit being movable in rotation with the needle cylinder, said circuits including means for providing a step voltage output when the level of signal received by the detector exceeds a predetermined threshold value; a means for supplying electrical power to the rotating needle cylinder bed; a monostable circuit for each needle capable of receiving said electrical power and producing an output pulse when triggered by the output from the said level detector circuit; and said magnetic actuator units having a permanent magnet having in association therewith an opposing winding for flux re-direction, the said winding being energizable in response to an output pulse produced by the monostable circuit suchwise as to re-direct the flux of the magnet; and in that in association with each magnetic actuator unit there is an armature rotatable with the magnetic actuator units, said armature being arranged to be normally attracted to and retained by the permanent magnet but releasable therefrom, upon said re-direction of flux in response to the output pulse of the monostable circuit, for exercising selective control over the corresponding knitting needle; the armature associated with each magnetic needle actuator unit comprising a spring wire rotatable with the needle cylinder bed which is adapted, when released from the permanent magnet of that unit, to initiate selective actuation of the corresponding needle, and wherein each knitting needle is actuated through the medium of a patterning jack housed in the same groove in the needle bed as that accomodating the said needle, the jack being adapted to be mechanically influenced to initiate desired behavior of the needle whenever the corresponding spring wire armature is released for movement away from its respective permanent magnet.

2. A circular knitting machine which includes a rotating tricked needle cylinder bed; individually operable knitting needles in said needle cylinder; pattern information carrier means movable synchronously with the machine but not rotatable with the needle cylinder; and an electronically controlled needle selection system which, at the dictates of the said pattern information carrier means, and through the butts associated with the needles, exercises selective and individual control over the latter so that some are influenced in one way and others in another way according to the nature of the patterned knitted fabric to be produced; said machine being characterized in that each individually operable knitting needle therein has its own magnetic actuator unit, all said magnetic actuator units being movable in' rotation with the needle cylinder, each magnetic actuator unit comprising, in combination, a detector responsive to signals transmitted thereto at the dictates of the movable pattern information carrier means; a level detector circuit for each needle, each circuit being movable in rotation with the needle cylinder, said circuits including means for providing a step voltage output when the level of signal received by the detector exceeds a predetermined threshold value; a means for supplying electrical power to the rotating needle cylinder bed; a monostable circuit for each needle capable of receiving said electrical power and producing an output pulse when triggered by the output from the said level detector circuit; and said magnetic actuator units having a permanent magnet having in association therewith an opposing winding for flux re-direction, the said winding being energizable in response to an output pulse produced by the monostable circuit suchwise as to re-direct the flux of the magnet; and in that in association with each magnetic actuator unit there is an armature rotatable with the magnetic actuator units, said armature being arranged to be normally attracted to and retained by the permanent magnet but releaseable therefrom, upon said re-direction of flux in response to the output pulse of the monostable circuit, for exercising selective control over the corresponding knitting needle; the armature associated with each magnetic needle actuator unit comprising a spring wire rotatable with the needle cylinder bed which is adapted, when released from the permanent magnet of that unit, to initiate selective actuation of the corresponding needle, and further including a cam, in advance of each needle selecting station for forcibly urging all the armatures seriatim from their relaxed condition into contact with their respective permanent magnets, preparatory to selected ones of these magnets having their flux paths changed to release the corresponding armatures, whereas the non-selected magnets are unaffected and retain their associated armatures all at the dictates of the moving pattern information carrier means.

3. A knitting machine according to claim 2, wherein the camming is so arranged that there is a maximum possible distance between the point at which a signal is transmitted to the level detector of each magnetic actuator unit and the point at which the corresponding armature, if selected, is released to initiate mechanical selection of the relevant needle, and the potential frequency of the signals determined by the moving pattern information carrier means is the same as the frequency of the relative movement of needle grooves past the means employed to transmit such signals to the level detectors whereby there is a substantial extension of the time available in which an electronic selection can be effected.

4. A circular knitting machine which includes a rotat ing tricked needle cylinder bed; individually operable knitting needles in said needle cylinder; pattern information carrier means movable synchronously with the machine but not rotatable with the needle cylinder; and an electronically controlled needle selection system which, at the dictates of the said pattern information carrier means, and through the butts associated with the needles, exercises selective and individual control over the latter so that some are influenced in one way and others in another way according to the nature of the patterned knitted fabric to be produced; said machine being characterized in that each individually operable knitting needle therein has its own magnetic actuator unit, all said magnetic actuator units being movable in rotation with the needle cylinder, each magnetic actuator unit comprising, in combination, a detector responsive to signals transmitted thereto at the dictates of the movable pattern information carrier means; a level detector circuit for each needle, each circuit being movable in rotation with the needle cylinder, said circuits including means for providing a step voltage output when the level of signal received by the detector exceeds a predetermined threshold value; a means for supplying electrical power to the rotating needle cylinder bed; a monostable circuit for each needle capable of receiving said electrical power and producing an output pulse when triggered by the output from the said level detector circuit; and said magnetic actuator units having a permanent magnet having in association therewith an opposing winding for flux re-direction, the said winding being energizable in response to an output pulse produced by the monostable circuit suchwise as to re-direct the flux of the magnet; and in that in association with each magnetic actuator unit there is an armature rotatable with the magnetic actuator units, said armature being arranged to be normally attracted to and retained by the permanent magnet but releaseable therefrom, upon said re-direction of flux in response to the output pulse of the monostable circuit, for exercising selective control over the corresponding knitting needle; the armature associated with each magnetic needle actuator unit comprising a spring wire rotatable with the needle cylinder bed which is adapted, when released from the permanent magnet of that unit, to initiate selective actuation of the corresponding needle, and wherein the permanent magnet of each magnetic needle actuator unit comprises a center pole piece of magnetic material around which is wound the opposing winding for flux re-direction, a pair of magnets at respectively opposite sides of the said center pole piece and, surrounding the whole, outer limbs of a ferrous material.

5. A circular knitting machine which includes a rotating tricked needle cylinder bed; individually operable knitting needles in said needle cylinder; pattern information carrier means movable synchronously with the machine but not rotatable with the needle cylinder; and an electronically controlled needle selection system which, at the dictates of the said pattern information carrier means, and through the butts associated with the needles, exercises selective and individual control over the latter so that some are influenced in one way and others in another way according to the nature of the patterned knitted fabric to be produced; said machine being characterized in that each individually operable knitting needle therein has its own magnetic actuator unit, all said magnetic actuator units being movable in rotation with the needle cylinder, each magnetic actuator unit comprising, in combination, a detector responsive to signals transmitted thereto at the dictates of the movable pattern information carrier means; a level detector circuit for each needle, each circuit being movable in rotation with the needle cylinder, said circuits including means for providing a step voltage output when the level of signal received by the detector exceeds a predetermined threshold value; a means for supplying electrical power to the rotating needle cylinder bed; a monostable circuit for each needle capable of receiving said electrical power and producing an output pulse when triggered by the output from the said level detector circuit; and said magnetic actuator units having a permanent magnet having in association therewith an opposing winding for flux re-direction, the said winding being energizable in response to an output pulse produced by the monostable circuit suchwise as to re-direct the flux of the magnet; and in that in association with each magnetic actuator unit there is an armature rotatable with the magnetic actuator units, said armature being arranged to be normally attracted to and retained by the permanent magnet but releaseable therefrom, upon said re-direction of flux in response to the output pulse of the monostable circuit, for exercising selective control over the corresponding knitting needle; the armature associated with each magnetic needle actuator unit comprising aspring wire rotatable with the needle cylinder bed which is adapted, when released from the permanent magnet of that unit, to initiate selective actuation of the corresponding needle, and wherein the level detectors in the needle actuator units include means responsive to light for providing a step voltage output when the level of light received by it exceeds a predetermined threshold value.

6. A knitting machine according to claim 5, including means for transmitting light signals to each said detector comprising a fiber-optic light guide comprising a flexible tube containing a bundle of light-transmitting fibers, and said pattern information carrier means includes a programmed control tape which is adapted to be driven synchronously with the machine and has one row of information per feed, one end of a corresponding fiber-optic light guide terminating in a reading head adjacent to the row while the other end of the said guide is so arranged as to be passed by, or to pass, the said detectors,

7. A knitting machine according to claim 6, wherein further fiber-optic light guides are provided at the side of the tape remote from the light-responsive detectors to pass light from at least one light source to the rows of information on the tape, via an illuminating head, the said light guides which extend between the light source and the illuminating head being in alignment with corresponding light guides extending between the reading head and the light-responsive detectors whereby whenever the tape permits of the passage of light therethrough the light will travel through the relevant light guide for a period of time determined by the speed of the tape, the resulting light signal being transmitted to the corresponding light-responsive detector.

8. A circular knitting machine which includes a rotating tricked needle cylinder bed; individually operable knitting needles in said needle cylinder; pattern information carrier means movable synchronously with the machine but not rotatable with the needle cylinder; and an electronically controlled needle selection system which, at the dictates of the said pattern information carrier means, and through the butts associated with the needles, exercises selective and individual control over the latter so that some are influenced in one way and others in another way according to the nature of the patterned knitted fabric to be produced; said machine being characterized in that each individually operable knitting needle therein has its own magnetic actuator unit, all said magnetic actuator units being movable in rotation with the needle cylinder, each magnetic actuator unit comprising, in combination, a detector responsive to signals transmitted thereto at the dictates of the movable pattern information carrier means; a level detector circuit for each needle, each circuit being movable in rotation with the needle cylinder, said circuits including means for providing a step voltage output when the level of signal received by the detector exceeds a predetermined threshold value; a means for supplying electrical power to the rotating needle cylinder bed; a monostable circuit for each needle capable of receiving said electrical power and producing an output pulse when triggered by the output from the said level detector circuit; and said magnetic actuator units having an permanent magnet having in association therewith an opposing winding for flux re-direction, the said winding being energizable in response to an output pulse produced by the monostable circuit suchwise as to re-direct the flux of the magnet; and in that in association with each magnetic actuator unit there is an armature rotatable with the magnetic actuator units, said armature being arranged to be normally attracted to and retained by the permanent magnet but releasable therefrom, upon said re-direction of flux in response to the output pulse of the monostable circuit, for exercising selective control over the corresponding knitting needle; the armature associated with each magnetic needle actuator unit comprising a spring wire rotatable with the needle cylinder bed which is adapted, when released from the permanent magnet of that unit, to initiate selective actuation of the corresponding needle, wherein said means for supplying electrical power to the cylinder bed comprises means for passing AC electrical power to rotating windings of a transformer and converter means for converting the power to D.C. electrical power, and means for passing the D.C. electrical power to the magnetic needle actuator units.

9. A knitting machine according to claim 8, in which said converter means includes supply packs for converting AC to DC current for operating the magnetic needle actuator units, and the DC power is passed to bus bar means which are in turn connected to electronic circuit boards each carrying the electronic circuitry for a group of the needle actuator units.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO- 1 855 Dated May 1973 Inventor) Herbert Brian Bliss-Hill and EIlC William Tewsley It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Please correct the heading of the above identified patent by adding the following priority information:

--[30] Foreign Application Priority Data December 17, 1969 Great Britain.......62077/69-.

Signed and sealed this 20th day of November 1973.

(SEAL) Attest:

EDWARD M.FIETCHER,JR.

RENE D wen Ema Attesting Officer Acting Commissioner of Patents )RM PO-1050 (10-69) uscoMM-Dc scan-Pee U.S. GOVERNMENT PRINTING OF F ICE 2 l9? 6-366-33, 

1. A circular knitting machine which includes a rotating tricked needle cylinder bed; individually operable knitting needles in said needle cylinder; pattern information carrier means movable synchronously with the machine but not rotatable with the needle cylinder; and an electronically controlled needle selection system which, at the dictates of the said pattern information carrier means, and through the butts associated with the needles, exercises selective and individual control over the latter so that some are influenced in one way and others in another way according to the nature of the patterned knitted fabric to be produced; said machine being characterized in that each individually operable knitting needle therein has its own magnetic actuator unit, all said magnetic actuator units being movable in rotation with the needle cylinder, each magnetic actuator unit comprising, in combination, a detector responsive to signals transmitted thereto at the dictates of the movable pattern information carrier means; a level detector circuit for each needle, each circuit being movable in rotation with the needle cylinder, said circuits including means for providing a step voltage output when the level of signal received by the detector exceeds a predetermined threshold value; a means for supplying electrical power to the rotating needle cylinder bed; a monostable circuit for each needle capable of receiving said electrical power and producing an output pulse when triggered by the output from the said level detector circuit; and said magnetic actuator units having a permanent magnet having in association therewith an opposing winding for flux re-direction, the said winding being energizable in response to an output pulse produced by the monostable circuit suchwise as to re-direct the flux of the magnet; and in that in association with each magnetic actuator unit there is an armature rotatable with the magnetic actuator units, said armature being arranged to be normally attracted to and retained by the permanent magnet but releasable therefrom, upon said re-direction of flux in response to the output pulse of the monostable circuit, for exercising selective control over the corresponding knitting needle; the armature associated with each magnetic needle actuator unit comprising a spring wire rotatable with the needle cylinder bed which is adapted, when released from the permanent magnet of that unit, to initiate selective actuation of the corresponding needle, and wherein each knitting needle is actuated through the medium of a patterning jack housed in the same groove in the needle bed as that accomodating the said needle, the jack being adapted to be mechanically influenced to initiate desired behavior of the needle whenever the corresponding spring wire armature is released for movement away from its respective permanent magnet.
 2. A circular knitting machine which includes a rotating tricked needle cylinder bed; individually operable knitting needles in said needle cylinder; pattern information carrier means movable synchronously with the machine but not rotatable with the needle cylinder; and an electronically controlled needle selection system which, at the dictates of the said pattern information carrier means, and through the butts associated with the needles, exercises selective and individual control over the latter so that some are influenced in one way and others in another way according to the nature of the patterned knitted fabric to be produced; said machine being characterized in that each individually operable knitting needle therein has its own magnetic actuator unit, all said magnetic actuator units being movable in rotation with the needle cylinder, each magnetic actuator unit comprising, in combination, a detector responsive to signals transmitted thereto at the Dictates of the movable pattern information carrier means; a level detector circuit for each needle, each circuit being movable in rotation with the needle cylinder, said circuits including means for providing a step voltage output when the level of signal received by the detector exceeds a predetermined threshold value; a means for supplying electrical power to the rotating needle cylinder bed; a monostable circuit for each needle capable of receiving said electrical power and producing an output pulse when triggered by the output from the said level detector circuit; and said magnetic actuator units having a permanent magnet having in association therewith an opposing winding for flux re-direction, the said winding being energizable in response to an output pulse produced by the monostable circuit suchwise as to re-direct the flux of the magnet; and in that in association with each magnetic actuator unit there is an armature rotatable with the magnetic actuator units, said armature being arranged to be normally attracted to and retained by the permanent magnet but releaseable therefrom, upon said re-direction of flux in response to the output pulse of the monostable circuit, for exercising selective control over the corresponding knitting needle; the armature associated with each magnetic needle actuator unit comprising a spring wire rotatable with the needle cylinder bed which is adapted, when released from the permanent magnet of that unit, to initiate selective actuation of the corresponding needle, and further including a cam, in advance of each needle selecting station for forcibly urging all the armatures seriatim from their relaxed condition into contact with their respective permanent magnets, preparatory to selected ones of these magnets having their flux paths changed to release the corresponding armatures, whereas the non-selected magnets are unaffected and retain their associated armatures all at the dictates of the moving pattern information carrier means.
 3. A knitting machine according to claim 2, wherein the camming is so arranged that there is a maximum possible distance between the point at which a signal is transmitted to the level detector of each magnetic actuator unit and the point at which the corresponding armature, if selected, is released to initiate mechanical selection of the relevant needle, and the potential frequency of the signals determined by the moving pattern information carrier means is the same as the frequency of the relative movement of needle grooves past the means employed to transmit such signals to the level detectors whereby there is a substantial extension of the time available in which an electronic selection can be effected.
 4. A circular knitting machine which includes a rotating tricked needle cylinder bed; individually operable knitting needles in said needle cylinder; pattern information carrier means movable synchronously with the machine but not rotatable with the needle cylinder; and an electronically controlled needle selection system which, at the dictates of the said pattern information carrier means, and through the butts associated with the needles, exercises selective and individual control over the latter so that some are influenced in one way and others in another way according to the nature of the patterned knitted fabric to be produced; said machine being characterized in that each individually operable knitting needle therein has its own magnetic actuator unit, all said magnetic actuator units being movable in rotation with the needle cylinder, each magnetic actuator unit comprising, in combination, a detector responsive to signals transmitted thereto at the dictates of the movable pattern information carrier means; a level detector circuit for each needle, each circuit being movable in rotation with the needle cylinder, said circuits including means for providing a step voltage output when the level of signal received by the detector exceeds a predetermined threshold value; a means for supplying electrical pOwer to the rotating needle cylinder bed; a monostable circuit for each needle capable of receiving said electrical power and producing an output pulse when triggered by the output from the said level detector circuit; and said magnetic actuator units having a permanent magnet having in association therewith an opposing winding for flux re-direction, the said winding being energizable in response to an output pulse produced by the monostable circuit suchwise as to re-direct the flux of the magnet; and in that in association with each magnetic actuator unit there is an armature rotatable with the magnetic actuator units, said armature being arranged to be normally attracted to and retained by the permanent magnet but releaseable therefrom, upon said re-direction of flux in response to the output pulse of the monostable circuit, for exercising selective control over the corresponding knitting needle; the armature associated with each magnetic needle actuator unit comprising a spring wire rotatable with the needle cylinder bed which is adapted, when released from the permanent magnet of that unit, to initiate selective actuation of the corresponding needle, and wherein the permanent magnet of each magnetic needle actuator unit comprises a center pole piece of magnetic material around which is wound the opposing winding for flux re-direction, a pair of magnets at respectively opposite sides of the said center pole piece and, surrounding the whole, outer limbs of a ferrous material.
 5. A circular knitting machine which includes a rotating tricked needle cylinder bed; individually operable knitting needles in said needle cylinder; pattern information carrier means movable synchronously with the machine but not rotatable with the needle cylinder; and an electronically controlled needle selection system which, at the dictates of the said pattern information carrier means, and through the butts associated with the needles, exercises selective and individual control over the latter so that some are influenced in one way and others in another way according to the nature of the patterned knitted fabric to be produced; said machine being characterized in that each individually operable knitting needle therein has its own magnetic actuator unit, all said magnetic actuator units being movable in rotation with the needle cylinder, each magnetic actuator unit comprising, in combination, a detector responsive to signals transmitted thereto at the dictates of the movable pattern information carrier means; a level detector circuit for each needle, each circuit being movable in rotation with the needle cylinder, said circuits including means for providing a step voltage output when the level of signal received by the detector exceeds a predetermined threshold value; a means for supplying electrical power to the rotating needle cylinder bed; a monostable circuit for each needle capable of receiving said electrical power and producing an output pulse when triggered by the output from the said level detector circuit; and said magnetic actuator units having a permanent magnet having in association therewith an opposing winding for flux re-direction, the said winding being energizable in response to an output pulse produced by the monostable circuit suchwise as to re-direct the flux of the magnet; and in that in association with each magnetic actuator unit there is an armature rotatable with the magnetic actuator units, said armature being arranged to be normally attracted to and retained by the permanent magnet but releaseable therefrom, upon said re-direction of flux in response to the output pulse of the monostable circuit, for exercising selective control over the corresponding knitting needle; the armature associated with each magnetic needle actuator unit comprising a spring wire rotatable with the needle cylinder bed which is adapted, when released from the permanent magnet of that unit, to initiate selective actuation of the corresponding needle, and wherein the level detectors in the needle actuAtor units include means responsive to light for providing a step voltage output when the level of light received by it exceeds a predetermined threshold value.
 6. A knitting machine according to claim 5, including means for transmitting light signals to each said detector comprising a fiber-optic light guide comprising a flexible tube containing a bundle of light-transmitting fibers, and said pattern information carrier means includes a programmed control tape which is adapted to be driven synchronously with the machine and has one row of information per feed, one end of a corresponding fiber-optic light guide terminating in a reading head adjacent to the row while the other end of the said guide is so arranged as to be passed by, or to pass, the said detectors.
 7. A knitting machine according to claim 6, wherein further fiber-optic light guides are provided at the side of the tape remote from the light-responsive detectors to pass light from at least one light source to the rows of information on the tape, via an illuminating head, the said light guides which extend between the light source and the illuminating head being in alignment with corresponding light guides extending between the reading head and the light-responsive detectors whereby whenever the tape permits of the passage of light therethrough the light will travel through the relevant light guide for a period of time determined by the speed of the tape, the resulting light signal being transmitted to the corresponding light-responsive detector.
 8. A circular knitting machine which includes a rotating tricked needle cylinder bed; individually operable knitting needles in said needle cylinder; pattern information carrier means movable synchronously with the machine but not rotatable with the needle cylinder; and an electronically controlled needle selection system which, at the dictates of the said pattern information carrier means, and through the butts associated with the needles, exercises selective and individual control over the latter so that some are influenced in one way and others in another way according to the nature of the patterned knitted fabric to be produced; said machine being characterized in that each individually operable knitting needle therein has its own magnetic actuator unit, all said magnetic actuator units being movable in rotation with the needle cylinder, each magnetic actuator unit comprising, in combination, a detector responsive to signals transmitted thereto at the dictates of the movable pattern information carrier means; a level detector circuit for each needle, each circuit being movable in rotation with the needle cylinder, said circuits including means for providing a step voltage output when the level of signal received by the detector exceeds a predetermined threshold value; a means for supplying electrical power to the rotating needle cylinder bed; a monostable circuit for each needle capable of receiving said electrical power and producing an output pulse when triggered by the output from the said level detector circuit; and said magnetic actuator units having an permanent magnet having in association therewith an opposing winding for flux re-direction, the said winding being energizable in response to an output pulse produced by the monostable circuit suchwise as to re-direct the flux of the magnet; and in that in association with each magnetic actuator unit there is an armature rotatable with the magnetic actuator units, said armature being arranged to be normally attracted to and retained by the permanent magnet but releasable therefrom, upon said re-direction of flux in response to the output pulse of the monostable circuit, for exercising selective control over the corresponding knitting needle; the armature associated with each magnetic needle actuator unit comprising a spring wire rotatable with the needle cylinder bed which is adapted, when released from the permanent magnet of that unit, to initiate selective actuation of the corresponding needle, whereiN said means for supplying electrical power to the cylinder bed comprises means for passing AC electrical power to rotating windings of a transformer and converter means for converting the power to D.C. electrical power, and means for passing the D.C. electrical power to the magnetic needle actuator units.
 9. A knitting machine according to claim 8, in which said converter means includes supply packs for converting AC to DC current for operating the magnetic needle actuator units, and the DC power is passed to bus bar means which are in turn connected to electronic circuit boards each carrying the electronic circuitry for a group of the needle actuator units. 